A major international study used brain imaging across 20 genetic mouse models of autism and nearly 2,000 humans to show that autism is not one condition neurobiologically. Two distinct subtypes emerged: one marked by underconnected brain networks tied to synaptic dysfunction, and another marked by overconnected networks tied to immune and gene-regulation pathways. These subtypes were highly reproducible and linked to different behavioral profiles. The findings offer direct empirical evidence that phenotypic variation in autism reflects real, measurable differences in underlying brain biology — a step that could eventually guide more targeted diagnosis and treatment strategies for individuals on the spectrum.
